Tool holders are used for clamping turning-, drilling-, reaming-, grinding-, and milling tools, and comprise a shrink fit chuck, which comprises a clamping section with an axial inner bore hole, in which the shaft of the tool can be mounted by shrink fit.
During the shrink fit process, the clamping section, whose inner bore hole comprises a slightly smaller inner diameter than the exterior diameter of the tool shaft, is expanded by heating, preferably by means of an induction coil, and cooled again after inserting the tool shaft, whereby a torque proof connection is established between the tool shaft and the shrink fit chuck.
Known embodiments of such tool holders, like e.g., shown in DE 199 44 440 C2 and DE 101 14 149 C2, already comprise very good vibration damping and torsion stability. However, they still comprise the risk that they become susceptible to vibration, in particular when used with extremely fast rotating tools, whereby the tool can perform a more or less oscillating movement about the longitudinal axis of the tool holder during its rotation, which can degrade the precision and reproducibility of the work pieces manufactured therewith. In order to still provide a high precision and reproducibility in spite of this, such tools must not be used with extremely fast rotation and also the feed and the cutting depth must not be selected too large. This way, however, the stock removing capacity is suboptimal; this means the machine running time per work piece produced is suboptimal.
Such tool holders, however, do not only have disadvantages with fast rotating tools. Also with non-rotating tools, deflections of the tool from the tool holder axis and vibrations can be caused by the impact of the work piece to be machined, which also degrade the precision of machining.
Other tool holders with shrink fit chuck are described in DE 202 00 298 U1 and DE 10 2004 019 869 A1 in the form of a telescoping tool holder, or as an additionally clamped tool holder. While tools can be held by the telescoping tool holder, on the one hand far away from the particular coupling, and on the other hand through deep and slender openings, extensive vibration compensation is possible with the additionally clamped tool holder. The first tool holder does not provide any dedicated vibration damping and the vibration damping of the second tool holder is configured rather complicated and technically complex.